HIS STORY Charlie, 28, lives in London and runs an online vintage furniture company, Mar-den

I was two when we lived in Santiago. We had been put in touch with an adoption agency. One night Mum and Dad piled my big sister Alice and me, in our pyjamas, into the car and drove to a house. A few hours later we were on our way back home and next to us was our tiny new brother Tom, three weeks old. At first he was just a toy, someone to cuddle, prod and stare at. But as we grew older, the inherent differences between us developed into a profound brotherly love.

Tom was so giggly, and Mum would try to make him laugh hysterically as he was eating supper, which we all loved to watch. He was energetic and sweet but could also be intense.

At school, when I was nine and Tom was seven, I saw him throw something at a ruffian in my year. The ruffian started to chase Tom, and I was terrified of what would happen. But Tom fixed him with such a powerful glare – a standoff – that he left Tom alone. I later learned that Tom had been provoked by the boy, and I've never forgotten how brave he was. From then on I knew he could handle himself. Naturally it bothered me that Tom was picked on – he was small, Chilean-looking, a bit different. He came out at 12, which is young but testament to how at ease and honest he's always been about himself. He said: "If they don't like me it's their problem."

Tom doesn't judge, criticise or interfere in other people's lives, and when I confided in him – he's very good to talk to – about starting a business, he couldn't have been more supportive. "You'll regret it if you don't," he said.

Tom probably thinks I should initiate arranging to meet up. I always look forward to going home, as he still lives there – it's such a treat to catch up and laugh together.

HIS STORY Tom, 26, runs the company Tom The Gardener in Richmond, where he lives

I always knew I was adopted, but it wasn't the subtext to my adolescence. If anything I felt like the cute baby of the family, not the adopted one. Charlie is my irresistibly cool older brother, into boyish stuff like football, rugby and activity, while my interests have always felt a bit geekier: comics, science, gardening, etc. I used to be hyperactive – borderline ADHD, I suppose – and this probably made it difficult to be around me. Especially as a sibling.

Growing up I liked making stuff and going on little walks by myself, but since we've got older our interests have overlapped. I started kayaking, and Charlie's just launched a business selling 20th-century furniture – which is creative. Plus, he now loves three-hour hikes in the country.

Once Charlie and I used rope and flowerpots to create a pulley system. He took his place high up in a tree, I stood below, and we passed messages to each other all afternoon.

I did experience bullying at school, which I wasn't particularly vocal about, and when it got bad Charlie wanted to do something about it. He told me recently that he'd briefed his rugby team about doing a potential intervention and they'd agreed to help him back me. It never came to that.

Part of the reason we work so well as brothers is because there's never been any rivalry. Charlie's never had "middle-child syndrome". He's kind and loving, and one of the few people who truly understands me. I'm a quiet person and tend to procrastinate. He'll come to our parents' house, where I live, and say: "Get up and do something!" We're both patient, something we've inherited from our dad, but you can tell he's trying to be patient while biting his tongue.